Dotan Cohen schreef:
On 24/01/2008, Richard Lynch <[EMAIL PROTECTED]> wrote:
On Wed, January 23, 2008 4:04 pm, Dotan Cohen wrote:
Is the "--" here not treated as the beginning of an SQL comment?
No, because it is inside the apostrophes.
The purpose of mysql_real_escape_string (or using prepared statements)
is to mark up (or separate) the DATA from the QUERY.
The data about to be put into the database being escaped by
mysql_real_escape_string is sufficient to be sure nobody is playing
games with apostrophe followed by -- which could, in theory, insert an
SQL comment or allow them to execute arbitrary SQL code.
In that case, the function:
function clean_mysql ($dirty) {
$dirty=str_replace ("--", "", $dirty);
$dirty=str_replace (";", "", $dirty);
$clean=mysql_real_escape_string($dirty);
return $clean;
}
Can be reduced to:
function clean_mysql ($dirty) {
$clean=mysql_real_escape_string($dirty);
return $clean;
}
or even:
function clean_mysql ($dirty)
{
return mysql_real_escape_string($dirty);
}
although I would make it part of a DB connection object so that
you can explicitly and transparently pass in the link id.
class myDBC
{
private $link;
function __construct($u, $p, $db, $cs)
{
// connect to given $db or throw exception
}
function cleanStr($s)
{
return mysql_real_escape_string($s, $this->link);
}
}
just a thought.
Which basically is the same as a simple mysql_real_escape_string? In
other words, mysql_real_escape_string itself is safe from SQL
injection?
not exactly - it assumes you will use the value as a quoted string in a query.
$s = clean_mysql("foo -- bar ; ' qux")
$q = "INSERT INTO foo (bar) VALUES ('$s')";
Dotan Cohen
http://what-is-what.com
http://gibberish.co.il
א-ב-ג-ד-ה-ו-ז-ח-ט-י-ך-כ-ל-ם-מ-ן-נ-ס-ע-ף-פ-ץ-צ-ק-ר-ש-ת
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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